The firing-lock case is eccentrically fitted in the hub of the block carrier, in such a position that the axis of the firing-pin is always in line with the bore of the gun. The vent bushing in the front end of the breech block through which the firing pin passes when in the fired position, is fitted eccentrically with reference to the breechblock. This eccentric arrangement of the breechblock, masks the point of the firing-pin and prevents any possible contact between the pin and the primer in the cartridge case when the block is unlocked. The block will be practically fully locked before any contact between the firing-pin and primer can take place.
Nomenclature of important parts of Breech & Firing Mechanism.
Mod. 1905:—
| Name of Part | Where located |
| Breech Block | On block carrier |
| Vent Bushing | Front end of block |
| Block Carrier | Hinged to jacket; supports block |
| Block Stop | Screwed into front face of carrier |
| Hinge Pin | Hinges carrier to jacket |
| Hinge Pin Catch | In hinge pin |
| Extractor | In breech recess |
| Extractor Lever | Mounted on hinge pin |
| Operating Lever | Pivoted on block carrier |
| Lever Pivot | Pivots lever on block carrier |
| Lever Latch | In operating lever |
| Lever Latch Spring | In operating lever, lower part |
| Lever Latch Pivot | In operating lever, lower part |
| Block Latch | In recess in carrier |
| Block Latch Spring | Around latch bolt |
| Firing Lock Case | In hub of the block carrier |
| Locking Bolt Nut and Pin | On firing lock case, rear face of carrier |
| Firing Pin | In axle hole, center of firing lock case |
| Firing Pin Spring | Around firing pin |
| Firing Spring Sleeve | Around firing pin spring |
| Sear | In slot in firing lock case |
| Trigger Fork | Rear end firing lock case |
| Trigger Shaft | On rear end firing lock case |
| Trigger Shaft Detent | On trigger shaft |
| Firing Pallet | On pallet shank |
| Pallet Shank | On recoil lug of gun |
| Firing Handle | On firing handle shaft |
| Firing Handle Bracket | Attached to right side of cradle |
| Firing Handle Shaft | Assembled in bracket, right side of cradle |
| Trip Latch | Attached to trip latch plunger |
| Trip Latch Plunger | Assembled to firing handle |
| Adjusting Screw | Assembled to firing handle bracket |
| Check Nut | Assembled in adjusting screw |
3 Inch Gun Carriage, Model of 1902.
Plan
THE GUN CARRIAGE.
The gun carriage for the 3-inch gun Model 1905 is of the type known as the long-recoil, in which the gun is permitted a sufficient length of recoil (about 45 inches) upon the carriage to render the latter stationary under firing stresses. The gun is mounted upon a cradle which forms a housing for the recoil controlling parts. The cradle rests upon the rocker and has a small traversing motion of 70 mils on each side of the axis of the carriage. The rocker is journaled upon the axle and its rear end is supported by the elevating mechanism, which is seated in the trail.
The principal parts of the carriage are the wheels, axle, trail and elevating mechanism forming the lower carriage, the cradle and recoil-controlling parts constituting the upper carriage, and the rocker and traversing mechanism intermediate between the two. In addition there are provided shields, ammunition carriers, the road brake, and the axle seats.
The Wheels and the Axle. The wheels are a modified form of the Archibald pattern, 56 inches in diameter, with 3-inch tires. The axle is hollow and forged from a single piece of steel. The wheels are held on by the wheel fastenings.